Printing apparatus and printing method

ABSTRACT

By effectively using a sheet feeding mechanism used for feeding a printing medium in a single transporting path for the purpose of another transporting path, a printing apparatus and a printing method that can simplify a configuration and reduce a size are provided. A first transporting path and a second transporting path are selectively used when an image is to be printed on a printing sheet. The first transporting path transports the printing sheet supplied by a sheet feeding roller from a printing sheet loading portion to a printing position. The second transporting path transports the printing sheet located at a position different from the printing sheet loading portion to the printing position. When the printing sheet is to be transported by the second transporting path, the sheet feeding roller is moved onto the second transporting path so as to transport the printing sheet in the second transporting path.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a printing apparatus that can print animage on a printing medium selectively using a plurality of transportingpaths and a printing method.

2. Description of the Related Art

Printing apparatuses include those in which a plurality of transportingpaths for a printing medium are formed.

Japanese Patent Laid-Open No. 2002-249241 describes a printing apparatusprovided with a transport path that transports a printing mediumsupplied from a sheet feeding cassette and a transport path thattransports a manually fed printing medium. The printing medium loaded onthe sheet feeding cassette is supplied by a sheet feeding roller andthen, transported by a transporting roller (intermediate roller). Thetransporting roller also transports the manually fed printing medium.When the manually fed printing medium is to be transported, the sheetfeeding roller is idly rotated.

Japanese Patent Laid-Open No. 2005-161839 describes a printing apparatusthat can print images on both sides of a printing medium. The printingapparatus is provided with a transport path that transports the printingmedium so that an image is printed on the front face of the printingmedium and a transport path that transports the printing medium so thatan image is printed on the back face of the printing medium. The formertransport path supplies the printing medium loaded on a sheet feedingcassette by a sheet feeding roller and then, transports the printingmedium by a transporting roller so as to oppose the front face of theprinting medium to a print head. As a result, an image is printed on thefront face of the printing medium. The latter transport path reversesthe printing medium printed on the front face so as to make the frontand back faces upside down and then, transports the printing mediumagain by the transporting roller so as to oppose the back face of theprinting medium to the print head. As a result, an image is printed onthe back face of the printing medium.

In this type of printing apparatus described in Japanese PatentLaid-Open No. 2005-161839, the same transporting roller is located inthe both transport paths, and the both transport paths are partiallymade common. When the printing medium whose front and back faces aremade upside down is to be transported by the latter transport path, thesheet feeding roller located in the former transport path does notfunction.

In Japanese Patent Laid-Open No. 2002-249241 and Japanese PatentLaid-Open No. 2005-161839, the transporting roller is commonly used inthe two transport paths, but the sheet feeding roller is used only forfeeding the printing medium in one transport path and not used for thepurpose other than the sheet feeding.

SUMMARY OF THE INVENTION

The present invention provides a printing apparatus and a printingmethod which can simplify a configuration and reduce a size byeffectively using a mechanism that feeds a printing medium in onetransport path for another transport path.

In the first aspect of the present invention, there is provided aprinting apparatus in which a printing medium is transported to aprinting position of a printing unit and an image is printed on theprinting medium, comprising: a first transporting path that transportsthe printing medium supplied by a supplying unit from a first positionwhere the printing medium is loaded to the printing position; and asecond transporting path that transports the printing medium located ata second position different from the first position to the printingposition, wherein the supplying unit can move onto the secondtransporting path so that the printing medium in the second transportingpath is transported along the second transporting path.

In the second aspect of the present invention, there is provided aprinting method in which a printing medium is transported to a printingposition of a printing unit and an image is printed on the printingmedium, wherein using: a first transporting path that transports theprinting medium supplied by a supplying unit from a first position wherethe printing medium is loaded to the printing position; and a secondtransporting path that transports the printing medium located at asecond position different from the first position to the printingposition, when the printing medium is transported by the secondtransporting path, the supplying unit is moved onto the secondtransporting path, and the printing medium in the second transportingpath is transported by the supplying unit.

According to the present invention, an image is printed on the printingmedium by selectively using the first transport path that transports theprinting medium supplied by the supplying unit to the printing positionand the second transport path that transports the printing mediumlocated at a position different from the supply destination of theprinting medium by the supplying unit to the printing position. When theprinting medium is to be transported by the second transport path, thesupplying unit is moved onto the second transport path so as totransport the printing medium in the second transport path by thesupplying unit so that the supplying unit of the first transport pathcan also perform a function as a transport unit of the second transportpath. As a result, the supplying unit of the first transport path can beeffectively used in the second transport path, and simplification of theconfiguration and size reduction of the printing apparatus can berealized.

The first transport path can be a transport path that transports theprinting medium so that an image is printed on one of the faces of theprinting medium, for example. Further, the second transport path can bea transport path that transports the printing medium so that an image isprinted on the other face of the printing medium in which an image hasbeen printed on one face, for example.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments (with reference to theattached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an appearance view of an inkjet printing apparatus of a firstembodiment of the present invention;

FIG. 2 is a perspective view of an engine portion in the printingapparatus in FIG. 1;

FIG. 3 is a perspective view of a transport portion and a sheetdischarging portion in the printing apparatus in FIG. 1;

FIG. 4 is a schematic configuration diagram of the engine portion in theprinting apparatus in FIG. 1;

FIG. 5 is a schematic diagram of an essential part during sheet feedingof the printing apparatus in FIG. 1;

FIG. 6 is a perspective view of a U-turn sheet feeding roller portion inthe printing apparatus in FIG. 1;

FIG. 7 is a schematic diagram for explaining a transport state of aprinting sheet in the printing apparatus in FIG. 1;

FIG. 8 is a schematic diagram for explaining a reversing state of theprinting sheet in the printing apparatus in FIG. 1.

FIG. 9 is a schematic diagram of the essential part during reversing ofthe printing sheet in the printing apparatus in FIG. 1;

FIG. 10 is a schematic diagram for explaining the reversing state of theprinting sheet in an inkjet printing apparatus of a second embodiment ofthe present invention; and

FIG. 11 is a schematic diagram of the essential part during reversing ofthe printing sheet in the printing apparatus in FIG. 10.

DESCRIPTION OF THE EMBODIMENTS

Modes for carrying out the present invention will be described referringto the attached drawings.

First Embodiment

A first embodiment of the present invention will be described based onFIGS. 1 to 9.

FIG. 1 is an appearance view of an inkjet printing apparatus of thisembodiment, and FIG. 2 is a perspective view of an engine portion in theprinting apparatus. FIG. 3 is a perspective view of a transport portionand a sheet discharging portion in the printing apparatus, and FIG. 4 isa schematic sectional diagram illustrating a transport state of aprinting sheet (printing medium) P of the printing apparatus.

A printing apparatus 900 of this example includes an engine portion 100,an exterior portion 200, a sheet feeding portion 1, a transport portion2, a carriage portion 3, a sheet discharging portion 4, a recoverydevice portion 5, a print head 30, a U-turn sheet feeding portion 7, atransport portion 8 for double-sided printing, and a control portion. Inthis example, as the sheet feeding portion for the printing sheet P, thesheet feeding portion 1 that supplies the printing sheet P from anupper-side position of the printing apparatus, and the U-turn sheetfeeding portion 7 that supplies the printing sheet P so as to turn in aU-turn from a lower-side position of the printing apparatus. However,the sheet feeding portion may be constituted only by the U-turn sheetfeeding portion 7.

(A) Sheet Feeding Portion

On an ASF (Automatic Sheet Feeding) base 15 of the sheet feeding portion1, a pressure plate 11 on which the printing sheets P are loaded, asheet feeding roller 12 that feeds the printing sheet P, a separationroller 13 a that separates the printing sheets P one by one, and areturn lever 14 are mounted. The return lever 14 is a lever that returnsthe printing sheet P to a loading position. A sheet feeding tray 16 thatholds the loaded printing sheets P is mounted on the ASF base 15 or theexterior 200.

The sheet feeding roller 12 forms a rod-state having an arc section. Onesheet feeding roller 12 is provided close to a reference position of theprinting sheet P, by which the printing sheet P is fed. A driving forceof the sheet feeding roller 12 is transmitted from a motor (hereinafterreferred to as an LF motor) 30 commonly used by the transport portion 2through a gear train.

A movable side guide 17 is movably provided on the pressure plate 11, bywhich a loading position of the printing sheet P is regulated. Thepressure plate 11 is rotatable around a rotation shaft connected to theASP base 15 and is urged by a pressure-plate spring 11 a (See FIG. 4) ina direction of the sheet feeding roller 12. At a portion of the pressureplate 11 opposing the sheet feeding roller 12, a separation sheet 13 bmade of a material with a large friction coefficient such as artificialleather is provided in order to prevent double-feeding of the printingsheet P loaded below. The pressure plate 11 is constituted so as to bebrought into contact with and separated from the sheet feeding roller 12by a pressure plate cam (not shown).

A separation roller holder 13 to which the separation roller 13 a thatseparates the printing sheets P one by one is rotatable around therotation shaft provided on the ASF base 15 and is urged by a separationroller spring (not shown) in a direction of the sheet feeding roller 12.On the separation roller 13 a, a clutch spring (not shown) is mounted,and if a load more than predetermined is applied, a portion to which theseparation roller 13 a is mounted can rotate. The separation roller 13 ais constituted so as to be brought into contact with and separated fromthe sheet feeding roller 12 by a separation roller release shaft (notshown) and a control cam (not shown).

The return lever 14 that returns the printing sheet P to the loadingposition is rotatably mounted on the ASF base 15 and is urged by areturn lever spring (not shown) in a releasing direction. When theprinting sheet P is to be returned to the loading position, the returnlever 14 is rotated by the control cam (not shown).

In a usual stand-by state, the pressure plate 11 is released by thepressure plate cam (not shown), and the separation roller 13 a isreleased by the control cam (not shown). The return lever 14 returns theprinting sheet P and is provided at a position blocking a loading portso that the printing sheet P does not enter the depth at loading. Sheetfeed is started in this stand-by state, and first, the separation roller13 a is brought into contact with the sheet feeding roller 12 by drivingof the motor. Then, the return lever 14 is released, and the pressureplate 11 is brought into contact with the sheet feeding roller 12through the printing sheet P.

Movement of the printing sheet P is restricted by a front-stageseparation portion (not shown) provided on the separation roller holder13, and only the predetermined number of printing sheets P are fed to anip between the sheet feeding roller 12 and the separation roller 13 a.The predetermined number of printing sheets P are separated at this nip,and only the uppermost printing sheet P is transported.

As will be described later, when a front end Pa of the printing sheet Preaches position between a main transporting roller 21 and a pinchroller 22 a, the pressure plate 11 is released by the pressure plate cam(not shown), and the separation roller 13 a is released by the controlcam (not shown). The return lever 14 is returned by the control cam (notshown) to the loading position. At this time, the printing sheet Phaving reached the nip between the sheet feeding roller 12 and theseparation roller 13 a can be returned to the loading position.

(B) Transport Portion

The transport portion 2 is mounted on a chassis 101 made of a bent andraised sheet metal. The transport portion 2 is provided with the maintransporting roller 21 that transports the printing sheet P and a PBsensor (not shown). The main transporting roller 21 is constituted suchthat a surface of a metal shaft is coated with ceramic fine particlesand is mounted on the chassis 101 by bearings 21 d receiving metalportions on both ends thereof. Between the bearing 21 d and the maintransporting roller 21, a transporting roller tension spring (not shown)is provided, and by urging the main transporting roller 21 so as toapply a predetermined load. The load is given during rotation of themain transporting roller 21 and stable transporting can be performed.

With the main transporting roller 21, a plurality of driven pinchrollers 22 a are brought into contact. The pinch roller 22 a is held bya pinch roller holder 22, and by urging the roller by a pinch rollerspring 22 b, the roller is pressed into contact with the maintransporting roller 21 and generates a transporting force for theprinting sheet P. The pinch roller holder 22 has its rotation shaftmounted in the bearing of the chassis 101 and is rotated around it.Further, on the pinch roller holder 22, a PE sensor lever 23 rotated bya front end Pa and a rear end Pb of the printing sheet P is provided,and the rotational movement is transmitted to the PE sensor (not shown).By means of the PE sensor, the front end Pa and the rear end Pb of theprinting sheet P are detected. A platen 25 is mounted on the chassis101.

In the above configuration, the printing sheet P fed to the transportportion 2 is guided by the pinch roller holder 22 and sent to a rollerpair of the main transporting roller 21 and the pinch roller 22 a. Atthis time, a guide flapper 83 has been rotated in an arrow direction E1in FIG. 4, and the printing sheet P is transported above it. Further,the front end Pa of the printing sheet P is detected by the PE sensor,by which a position to be printed on the printing sheet P is acquired.In addition, the printing sheet P is transported on the platen 25 by theroller pair 21 and 22 a rotated by an LF motor 26. On the platen 25, arib forming a transporting reference face of the printing sheet P isformed so that an opposing interval between the printing sheet P and theprint head 30 is managed and occurrence of a ruffling phenomenon of theprinting sheet P is suppressed together with the sheet dischargingportion 4, which will be described later.

In order to drive the main transporting roller 21, rotation of the LFmotor (DC motor, for example) 26 is, as shown in FIG. 3, transmitted byan LF timing belt 26 a to an LF pulley 21 c provided on the shaft of themain transporting roller 21. On the shaft of the main transportingroller 21, an LF code wheel 21 a that detects a transporting amount ofthe printing sheet P transported by the main transporting roller 21 isprovided. On the LF code wheel 21 a, marking is applied with a pitch of150 to 300 lpi (line/inch), and an LF encoder 21 b that reads themarking is mounted on the chassis 101 at a position adjacent to the LFcode wheel 21 a.

At a position on the downstream side in the transporting direction ofthe printing sheet from the main transporting roller 21, an inkjet printhead 30 that prints an image on the basis of image information isprovided. The print head 30 in this example is configured such that areplaceable ink tank 500 is mounted, and four tanks are provided so thatdifferent types of ink are ejected. The print head 30 can eject ink froma nozzle by using an ejection energy generating element such as anelectrothermal conversion element (heater) or a piezoelectric element.If the electrothermal conversion element is used, for example, heat isapplied to ink so as to generate foam and the ink can be ejected fromthe nozzle using the foaming energy. By means of the ink ejected fromthe nozzle, an image is printed on the printing sheet P.

(C) Carriage Portion

The carriage portion 3 is provided with a carriage 31 on which the printhead 30 can be mounted. The carriage 31 is reciprocally moved in aprimary scanning direction of an arrow X crossing (orthogonal in thisexample) a transporting direction (secondary scanning direction) of anarrow Y of the printing sheet P. Thus, a guide sheet-metal rail 32 bthat guides the carriage 31 and a carriage unit of the chassis 101 thatholds an upper end portion of the carriage 31 are provided. The guidesheet-metal rail 32 b has an L-shaped section. In order to stabilize anattitude of the carriage 31 in the secondary scanning direction of thearrow Y with respect to the guide sheet-metal rail 32 b, a bearing plate37 is mounted on the carriage 31. In order to urge the bearing plate 37on the downstream side in the feeding direction of the printing sheet P,a bearing plate spring (not shown) is provided. By sandwiching the guidesheet-metal rail 32 b between the carriage 31 and the bearing plate 37using this urging force, the attitude of the carriage 31 in thesecondary scanning direction of the arrow Y is stabilized.

The vertical direction of the carriage 31 is regulated by being broughtinto contact with the L-shaped guide sheet-metal rail 32 b by its ownweight of the carriage portion 3. With regard to the rotationaldirection of the carriage 31, the attitude is stabilized by a slidingportion between the carriage 31 and a carriage-unit upper part of thechassis 101 that holds an upper end portion of the carriage 31.

On the carriage 31, a carriage cover 38 is mounted, and the carriagecover 38 functions as a guiding member when a user attaches the printhead 30 to the carriage 31 and also functions as a member that holds theink tank 500. The guide sheet-metal rail 32 b is mounted on the chassis101, and the position of the carriage 31 is adjusted at factries byadjusting the position of the guide sheet-metal rail 32 b.

The carriage 31 is driven by a CR motor 33 mounted on the chassis 101through a CR timing belt 33 a. The CR timing belt 33 a is extended by anidler pulley 33 b and connected to the carriage 31. A code strip 34 thatdetects a moving position of the carriage 31 is provided in parallelwith the CR timing belt 33 a, and the code strip 34 is marked with apitch of 150 to 300 lpi (line/inch). On the carriage 31, an encoder (notshown) that reads the marking is provided.

In the above configuration, when an image is to be printed on theprinting sheet P, the printing sheet P is transported by the roller pair21 and 22 a, and a position in a row direction on which the image is tobe printed (position in the transporting direction of the printing sheetP) is positioned at a printing position of the print head 30. Afterthat, while the carriage 31 is moved with the print head 30 in theprimary scanning direction by a signal from the control portion, ink isejected from the print head 30 so that the ink is landed at a positionin a column direction where the image is to be printed (position in theprimary scanning direction), and the image is printed. By repeating thetransporting operation of the printing sheet P and the scanning by theprint head 30, the image is sequentially printed on a front face (oneface) or a back face (the other face) of the printing sheet P opposingthe print head 30.

(D) Sheet Discharging Portion

The sheet discharging portion 4 is constituted by a first sheetdischarging roller 41, a spur 41 e that can be driven and rotated incontact with the first sheet discharging roller 41 with a predeterminedpressure, a gear train that transmits rotational movement of the maintransporting roller 21 to the first sheet discharging roller 41 and thelike.

The first sheet discharging roller 41 is mounted on the platen 25 so asto be located on the downstream side in the feeding direction of theprinting sheet P and is configured such that a plurality of rubberportions are provided on the metal shaft. The first sheet dischargingroller 41 is driven by transmission of a driving force of the maintransporting roller 21 through a sheet ejection idler gear 43.

The spur 41 e is formed by molding a SUS thin plate with a plurality ofprojecting shapes provided on the periphery integrally into a resinportion and is mounted on a spur holder 44 a. The spur 41 e is mountedon the spur holder 44 a by a spur spring (not shown) in which a coilspring is provided in a rod state and the spur is pressed onto the firstsheet discharging roller 41 or the like. The plurality of spurs 41 einclude those with a function mainly to produce a transporting force ofthe printing sheet P opposite the rubber portion of the first sheetdischarging roller 41 and those with a function to mainly suppressfloating the printing sheet P during printing opposite a positionwithout rubber portion of the first sheet discharging roller 41.Further, in order to suppress deformation of the spur holder 44 a anddeformation of the chassis 101, a spur stay 44 b, which is aplate-shaped metal, is mounted.

With the above configuration, the printing sheet P with the imageprinted by the carriage portion 3 is transported while being sandwichedat the nip between the first sheet discharging roller 41 and the spur 41e and discharged onto a sheet discharge tray 49.

(E) U-Turn Sheet Feeding Portion

On a base 73 of the U-turn sheet feeding portion (supplying unit) 7, aprinting sheet loading portion 9 on which the printing sheet P isloaded, a U-turn sheet feeding roller (supply roller) 71 that feeds theprinting sheet P, a U-turn intermediate transporting roller 79, a U-turnseparation member 72 and the like are mounted. The intermediatetransporting roller 79 transports the printing sheet P, and theseparation member 72 separates the printing sheets P. In this example,the intermediate transporting roller 79 is used but not limited to that,and the intermediate transporting roller 79 does not have to be provideddepending on a size of a printing medium that can be loaded on theloading portion 9, that is, a specification of the loading portion 9.

On the base 73, a U-turn sheet feeding shaft 74 that transmits a drivingforce to the sheet feeding roller 71, a U-turn sheet feeding arm 75 andthe like are mounted. The sheet feeding arm 75 is capable of pivotalrotation around the shaft 74, and the sheet feeding roller 71 is mountedthereon. A transporting path (first transporting path) that transportsthe printing sheet from the U-turn sheet feeding portion 7 isconstituted mainly by a U-turn sheet-feeding rear guide 76, a lower faceof the ASF base 15, the base 73, the guide flapper 83, and the pinchroller holder 22.

A driving force of the sheet feeding roller 71 may be supplied from theabove-mentioned transport portion 2 through a belt or a gear train ormay be supplied from an independent driving force. However, if the maintransporting roller 21 is rotated backward in a direction of an arrow C2in FIG. 4, it is necessary to switch the sheet feeding roller 71 to berotated or not. In the case of this example, such switching is madeusing a PG motor (not shown) of a recovery device portion 5 in FIG. 2.However, the configuration is not limited to that, and such aconfiguration that a trigger is given to transmission of the drivingforce by movement of the carriage portion 3, for example, may beemployed. The recovery device portion 5 performs recovery processingthat maintains an ink ejection state of the print head 30 favorable. Therecovery processing can include processing to eject or to suck and ejectink not contributing to printing of an image from the nozzle of theprint head 30, processing to wipe a face of the print head 30 on whichthe nozzles are formed, and the like.

Subsequently, an ink supply method from the U-turn sheet feeding portion7 will be described using FIGS. 4 and 5.

As shown in FIG. 4, when the printing sheet P is set on the loadingportion 9 (hereinafter, the loaded printing sheet is also referred to as“printing sheet P0”) and a driving force of the LF motor 26 istransmitted to the sheet feeding roller 71, the LF motor 26 is rotatedbackward. The backward rotation direction of the LF motor 26 is abackward rotation direction (arrow C2 direction) when the printing sheetP is transported by the main transporting roller 21 to the upstream sidein the transporting direction. The sheet feeding roller 71 is rotated ina direction that feeds the printing sheet P to the main transportingroller 21 and feeds the printing sheet P as shown by the arrow A in FIG.4. The plurality of printing sheets P fed from the loading portion 9 hitthe U-turn separation member 72 and are separated, and only the singlesheet located on top is fed.

The separated single printing sheet P is transported to the arrow Bdirection in a transporting path L in FIG. 4. The front end Pa of theprinting sheet P is detected when it hits the PE sensor lever 23, bywhich a printing position on the printing sheet P on which the image isto be printed is acquired. The printing sheet P is further transportedand the front end Pa of the printing sheet P is pressed into the nipbetween the main transporting roller 21 rotated backward in the arrow C2direction and the pinch roller 22 a, and the position of the front endPa is adjusted (skew correcting operation).

After that, by rotating the LF motor 26 forward and by rotating the maintransporting roller 21 in the arrow C1 direction, the front end of theprinting sheet P is bitten by the nip of the roller pair 21 and 22 a. Inthe forward rotation of the LF motor 26, the U-turn sheet feeding roller71 is not driven, but the U-turn sheet feeding roller 71 is brought intoa free state and rotated along with the transporting of the printingsheet P.

After that, similarly to the above-mentioned case, the printingoperation and the sheet-discharge operation are performed for theprinting sheet P.

When the printing on the printing sheet P is finished, the sheet feedingarm 75 is pivotally rotated around the shaft 79 in a direction of anarrow D2 in FIG. 5, and the sheet feeding roller 71 is lifted up andretreated upward from the printing sheet P0 loaded on the loadingportion 9. In this example, an operation to turn so as to lift up thesheet feeding arm 75 is triggered by the carriage portion 3. However,not limited to that, the sheet feeding arm 75 may be lifted up inconjunction with the forward-rotation driving of the main transportingroller 21.

(F) Transporting Portion for Double-Sided Printing

FIG. 6 is a perspective view of a transporting portion 8 fordouble-sided printing in this embodiment, and FIGS. 7 to 9 are schematicdiagrams for explaining a transporting state of the printing sheet P inthis embodiment.

FIG. 6 shows a transporting path 81 constituting the transportingportion 8 and the sheet feeding roller 71 in the above-mentioned U-turnsheet feeding portion 7. In a guide member forming the transporting path81 located below the sheet feeding roller 71, a hole 81A is formed.During sheet feeding from the loading portion 9, as shown in FIG. 5, thesheet feeding roller 71 enters the hole 81A so as to feed the printingsheet P0 located below the transporting path 81.

FIG. 7 shows a state in which printing has been finished to the vicinityof the rear end Pb on the printing sheet P fed from the sheet feedingportion 1 or the U-turn sheet feeding portion 7. The rear end Pb of theprinting sheet P is in a state bitten by the nip between the maintransporting roller pair 21 and 22 a as in the figure. The printing onthe printing sheet P is finished in this state and then, an operationmoves on to the reversing operation.

First, from this state, the guide flapper 83 is rotated in a directionof an arrow E2 in FIG. 8, and an inlet of the transporting path 81 isopened. When the carriage 31 is moved to a predetermined position in theprimary scanning direction, the guide flapper 83 is capable of drivingusing the moving force of the carriage 31. For example, if the carriage31 is moved from one direction to a position close to an end portion inthe movement range, when the carriage 31 is brought into contact with aconnecting member connected to the guide flapper 83, it can move theguide flapper 83 in a direction to open the inlet of the transportingpath 81. After that, when the carriage 31 is moved to the otherdirection and separated from the connecting member, it can move theguide flapper 83 in a direction to close the inlet of the transportingpath 81. However, a driving method of the guide flapper 83 is notlimited to this type of method but a driving force may be obtained froma driving source different from the driving source of the carriage 31.

In a state in which the guide flapper 83 is opened in the arrow E2direction as above, the LF motor 26 is rotated backward so as to rotatethe main transporting roller 21 backward in the arrow C2 direction inFIG. 8, and the printing sheet P is reversed and transported to adirection of an arrow F. At that time, the PE sensor lever 23 is rotatedin an arrow G direction by the front end (rear end before the reversing)Pb after the reversing of the printing sheet P. By detecting therotation with the PE sensor (not shown), the front end Pb afterreversing of the printing sheet P having been transported, and theposition of the printing sheet P can be acquired.

After the fact that the printing sheet P has entered the transportingpath (second transporting path) 81 is detected by the PE sensor (notshown), a guide member 82 housed in a lower part of the transportingpath 81 is moved to a position blocking the hole 81A of the transportingpath 81 as shown in FIG. 9. As a result, the guide member 82 forms apart of the transporting path 81. When the front end Pb after thereversing of the printing sheet P has reached under the sheet feedingroller 71, the shaft 74 is driven so as to pivotally rotate the sheetfeeding arm 75 in an arrow D1 as shown in FIG. 9. As a result, the sheetfeeding roller 71 is brought into contact with the printing sheet Phaving been transported. Since the guide member 82 blocks the hole 81Aof the transporting path 81 at this time, the sheet feeding roller 71 isnot lowered to a position for feeding the printing sheet P0 in theloading portion 9 but functions as a transporting roller for theprinting sheet P.

In this example, the position of the printing sheet P is accuratelydetected by the PE sensor (not shown). The position of the printingsheet P during transporting in a direction passing through thetransporting path 81 may be detected using another sensor without usingthe PE sensor lever 23 or the PE sensor (not shown).

FIG. 9 shows a state in which the front end Pb after the reversing ofthe printing sheet P has entered the transporting path L. By rotatingthe guide flapper 83 in the arrow E1 direction as shown in FIG. 4 whiletransporting the printing sheet P as it is, the printing sheet P passesover the guide flapper 83. Then, the front end Pb after the reversing ofthe printing sheet P is pressed into the nip between the maintransporting roller 21 rotated backward in the arrow C2 direction andthe pinch roller 22 a, and the position of the front end Pb is adjusted(skew correcting operation). After that, the front end Pb after thereversing of the printing sheet P is bitten by the nip between the maintransporting roller 21 rotated forward in the arrow C1 direction and thepinch roller 22 a by rotating the LF motor 26 forward. The feedingroller 71 is not driven by the forward rotation of the LF motor 26 andbrought into a free state and rotated along with the transporting of theprinting sheet P.

Timing to shut off the driving of the feeding roller 71 is not limitedto the timing when the front end Pb after the reversing of the printingsheet P is bitten by the nip between the roller pair 21 and 22 a. Forexample, it may be the timing when the front end Pb is bitten by the nipbetween the intermediate transporting roller pair 79 and 79 a.

After that, the operations of printing on the printing sheet P and sheetdischarging are the same as the above-mentioned case. Since the printingsheet P after the reversing has its back face opposing the print head30, the image is printed on the back face.

In the case of this example, when the printing sheet P after thereversing is to be transported, the timing to start rotation of thesheet feeding roller 71 should be after the front end Pb after thereversing of the printing sheet P has reached the sheet feeding roller71, and then, the printing sheet P is transported by the maintransporting roller 21 and the sheet feeding roller 71 in collaboration.In a case where a distance between the main transporting roller 21 andthe sheet feeding roller 71 is large, if the distal end Pb after thereversing of the printing sheet P has reached the position of the sheetfeeding roller 71, the rear end (front end before the reversing) Paafter the reversing of the printing sheet P may be removed from the nipof the main transporting roller 21. In that case, the subsequenttransporting of the printing sheet P can be performed only by the sheetfeeding roller 71, and a configuration that a relation of speed increaseto speed reduction between the main transporting roller 21 and the sheetfeeding roller 71 does not have to be considered can be employed. As aresult, transporting of the printing sheet P with higher accuracy can berealized.

In this example, if the printing is to be performed on the back face ofthe printing sheet P in an automatic double-sided printing mode, theprinting on the front face of the printing sheet P is performed till therear end Pb of the printing sheet P is removed from the nip of theroller pair 21 and 22 a. That is because if the rear end of the printingsheet P is removed from the nip of the roller pair 21 and 22 a andtransported to the downstream side in the transporting direction, thereis a fear that the front end Pb after the reversing is not bitten by theroller pair 21 and 22 a when the printing sheet P is reversed and fedback. However, by adding a configuration that the pinch roller holder 22and the pinch roller 22 a are released upward, the printing can be madeto the full of the rear end Pb on the front face of the printing sheetP.

The transporting path (second transporting path) 81 forms a transportingpath for transporting from a position (second position) on thetransporting path where the printing sheet P after the image is printedon the front face is located to the printing position of the print head30 after the printing sheet P is reversed. During the transporting ofthe printing sheet P after the reversing, the sheet feeding roller 71functions as a transporting roller. In the printing apparatus of thisexample, the transporting path (second transporting path) formed by thetransporting path 81 and the transporting path (first transporting path)for transporting the printing sheet P having been fed from the loadingportion 9 to the printing position of the print head 30 are formed.These transporting paths include the transporting path L as a commonpath for the both.

Second Embodiment

FIGS. 10 and 11 are diagrams for explaining a second embodiment of thepresent invention. In this embodiment, a configuration of thetransporting portion for double-sided printing is different from theabove-mentioned first embodiment. The difference will be describedbelow.

(F) Transporting Portion for Double-Sided Printing

FIG. 10 is an explanatory diagram of the printing sheet loading portion9 in this embodiment, and FIG. 11 is an explanatory diagram of a feedingstate of the printing sheet P in this embodiment. In this embodiment,instead of the guide member 82 in the first embodiment that blocks thehole 81A of the transporting path 81, the loading portion 9 is urgedupward in the configuration.

In this example, the loading portion 9 located below the transportingpath 81 is pressed downward by a cam (not shown) mounted on the base 73in the occasions other than the double-sided printing. During thedouble-sided printing, as shown in FIG. 10, after it is detected by thePE sensor (not shown) that the reversed printing sheet P has entered thetransporting path 81, the cam (not shown) is rotated and releases thepressing on the loading portion 9 downward. Therefore, as shown in FIG.11, an urging spring 97 mounted at a lower part of the loading portion 9urges the loading portion 9 upward. As a result, the printing sheet P0loaded on the loading portion 9 blocks the hole 81A of the transportingpath 81 and forms a part of the transporting path 81.

In this example, it is configured that the entire loading portion 9 isurged toward the transporting path 81. However, the present invention isnot limited to that, and it may be so configured that the printing sheetP0 is urged using the pressure plate or the pressure plate springprovided at the front end of the loading portion 9, for example. In thiscase, too, the printing sheet P0 loaded on the loading portion 9 blocksthe hole 81A of the transporting path 81 and forms a part of thetransporting path 81.

When the front end (rear end before the reversing) Pb after thereversing of the printing sheet P has reached below the sheet feedingroller 71, the shaft 74 is driven so as to pivotally rotate the sheetfeeding arm 75 in the arrow D1 direction. As a result, the sheet feedingroller 71 is brought into contact with the printing sheet P. At thistime, since the hole 81A of the transporting path 81 is blocked by theprinting sheet P0 of the loading portion 9, the sheet feeding roller 71is not lowered to a position for feeding the printing sheet P0 in theloading portion 9 but functions as a transporting roller that transportsthe printing sheet P. A stopper portion 81B is provided below thetransporting path 81 so that the printing sheet P0 loaded on the loadingportion 9 is not fed at that time. Therefore, the printing sheet P0loaded on the loading portion 9 is not fed. If there is no printingsheet P0 on the loading portion 9, the loading portion 9 is pressedagainst the lower part of the transporting path 81 by the urging spring91, and the hole 81A of the transporting path 81 is blocked by an innerbottom face of the loading portion 9.

Other Embodiments

In the second embodiment, it is configured such that the sheet feedingroller 71 is moved by swing of the sheet feeding arm 75, and theprinting sheets P0 are separated by the separation member 72. However,it may be so configured such that the sheet feeding roller 71 is movedvertically or the printing sheets P0 are separated without using theseparation member 72. For example, the shaft 74 may be verticallymovable and the sheet feeding roller may be supported by the shaft 74.Alternatively, without using the separation member 72, a configurationthat the printing sheets P0 are separated by a separation roller (retardseparation) similarly to the supply portion 1 may be employed.

The present invention can be widely applied to a printing apparatusprovided at least with two transporting paths (first and secondtransporting paths) for transporting a printing medium in printingapparatuses that print an image on the printing medium by transportingthe printing medium to a printing position of a printing unit.Therefore, as a printing method, various methods using a print head canbe employed other than an inkjet print head. Further, in addition to theserial scanning type printing apparatus as in the above-mentionedembodiments, a full-line type printing apparatus using a lengthy printhead extending in a width direction of a printing region in the printingmedium may be used.

Further, it is only necessary that the first transporting path is atransporting path for transporting the printing medium supplied by asupplying unit from a first position on which the printing medium isloaded to a printing position. The first position is not limited to aprinting sheet loading portion as in the above-mentioned embodiments,that is, not limited to a position on a supply tray on which a pluralityof printing mediums can be loaded, but may be a position on which atleast a single printing medium is loaded. Further, the firsttransporting path is not limited only to a configuration including apath for discharging the printing medium in which an image is printed onone face at the printing position through a second position as in theabove-mentioned embodiment but it is only necessary that thetransporting path can transport the printing medium supplied from thefirst position to the printing position.

Further, it is only necessary that the second transporting path is asecond transporting path for transporting the printing medium located atthe second position different from the first position to the printingposition. The second position is not limited only to a transportingposition of the printing medium in which an image is printed on one faceas in the above-mentioned embodiments but may be a position for manuallyfeeding of the printing medium. Essentially, it is only necessary thatthe second is different from the first position. In addition, the secondtransporting path is not limited only to a configuration in which theprinting medium located at the second position is reversed andtransported to the printing position so that an image is printed on theother face of the printing medium but it is only necessary that thesecond transporting path can transport the printing medium located atthe second position to the printing position.

The first transporting path and the second transporting path can includea common path common to the both, and the common path can be providedwith a transporting roller constituting a transporting unit as in theabove-mentioned embodiments.

It is only necessary that the supplying unit can move on the secondtransporting path so that the printing medium in the second transportingpath is transported along the second transporting path. In theabove-mentioned embodiments, the sheet feeding roller (supply roller)constituting the supplying unit is moved to the position in FIG. 9.Further, the supplying unit can be configured to block the secondtransporting path when it is located on the first transporting path. Inthe above-mentioned embodiments, the sheet feeding roller (supplyroller) constituting the supplying unit blocks the second transportingpath as in FIG. 5.

The supply roller constituting the supplying unit can move to each of aposition on the first transporting path and a position on the secondtransporting path by providing a rotatable arm as in the above-mentionedembodiments. In addition, the configuration to move the supply roller isnot limited only to the above-mentioned embodiments.

It may be so configured that a part of the second transporting path isformed by an upper face of a guide member located above a supply tray,and the supply roller is opposed to the upper face of the guide memberwhen moved onto the second transporting path and is opposed to theprinting medium loaded on the supply tray when moved onto the firsttransporting path. In this case, the supply roller can move to each ofthe position on the first transporting path and the position on thesecond transporting path through a hole formed in the guide member. Inaddition, when the printing medium is to be transported by the secondtransporting path, a blocking unit that forms a part of the secondtransporting path by blocking the hole in the guide member can beprovided. As the blocking unit, as in the above-mentioned firstembodiment, a guide member as a blocking member located below the guidemember and movable to the position to open and block the hole may beincluded. Further, as in the above-mentioned second embodiment, byurging the supply tray upward, the hole can be also blocked by theprinting medium loaded on the supply tray or the inner bottom face ofthe supply tray. The configuration of the blocking unit is not limitedonly to these embodiments.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2008-322164, filed Dec. 18, 2008, which is hereby incorporated byreference herein in its entirety.

1. A printing apparatus in which a printing medium is transported to aprinting position of a printing unit and an image is printed on theprinting medium, comprising: a first transporting path that transportsthe printing medium supplied by a supplying unit from a first positionwhere the printing medium is loaded to the printing position; and asecond transporting path that transports the printing medium located ata second position different from the first position to the printingposition, wherein the supplying unit can move onto the secondtransporting path so that the printing medium in the second transportingpath is transported along the second transporting path.
 2. The printingapparatus according to claim 1, wherein the first transporting path andthe second transporting path include a common path common to the bothpaths, and the common path is provided with a feeding unit thattransports the printing medium.
 3. The printing apparatus according toclaim 1, wherein the first transporting path includes a path thatdischarges the printing medium in which an image is printed on one faceat the printing position through the second position, and the secondtransporting path reverses the printing medium at the second positionand transports the printing medium to the printing position so that animage is printed on the other face of the printing medium.
 4. Theprinting apparatus according to claim 1, wherein the supplying unitblocks the second transporting path when the supplying unit is locatedon the first transporting path.
 5. The printing apparatus according toclaim 1, wherein a supply tray on which a plurality of the printingmediums can be loaded is provided at the first position, and thesupplying unit includes a supply roller that supplies an uppermost onein the printing mediums loaded on the supply tray to the firsttransporting path.
 6. The printing apparatus according to claim 5,wherein the supply roller is movable to a position on the firsttransporting path and a position on the second transporting path,respectively.
 7. The printing apparatus according to claim 6, whereinthe supply roller is provided at a rotatable arm.
 8. The printingapparatus according to claim 6, wherein a part of the secondtransporting path is formed by an upper face of a guide member locatedabove the supply tray, and the supply roller opposes the upper face ofthe guide member when the supply roller moves onto the secondtransporting path and opposes the printing medium loaded on the supplytray when the supply roller moves onto the first transporting path. 9.The printing apparatus according to claim 8, wherein the supply rolleris movable to a position on the first transporting path and a positionon the second transporting path, respectively, through a hole formed inthe guide member, and a blocking unit is provided that forms a part ofthe second transporting path by blocking the hole when the printingmedium is transported by the second transporting path.
 10. The printingapparatus according to claim 9, wherein the blocking unit includes ablocking member located below the guide member and movable to a positionthat opens and blocks the hole.
 11. The printing apparatus according toclaim 10, wherein the blocking unit urges the supply tray upward so thatthe hole is blocked by the printing medium loaded on the supply tray orthe inner bottom face of the supply tray.
 12. The printing apparatusaccording to claim 1, wherein the printing unit prints an image using aninkjet print head that can eject ink.
 13. A printing method in which aprinting medium is transported to a printing position of a printing unitand an image is printed on the printing medium, wherein using: a firsttransporting path that transports the printing medium supplied by asupplying unit from a first position where the printing medium is loadedto the printing position; and a second transporting path that transportsthe printing medium located at a second position different from thefirst position to the printing position, when the printing medium istransported by the second transporting path, the supplying unit is movedonto the second transporting path, and the printing medium in the secondtransporting path is transported by the supplying unit.